/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package hivemall.tools.mapred;

import static hivemall.utils.hadoop.WritableUtils.val;
import hivemall.utils.hadoop.HadoopUtils;

import javax.annotation.Nullable;

import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.MapredContext;
import org.apache.hadoop.hive.ql.exec.MapredContextAccessor;
import org.apache.hadoop.hive.ql.exec.UDF;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.udf.UDFType;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.JobConf;

/**
 * @since Hive 0.12.0
 */
@Description(name = "jobconf_gets", value = "_FUNC_() - Returns the value from JobConf")
@UDFType(deterministic = false, stateful = true)
public class JobConfGetsUDF extends UDF {

    public Text evaluate() throws HiveException {
        return evaluate(null);
    }

    public Text evaluate(@Nullable final String regexKey) throws HiveException {
        MapredContext ctx = MapredContextAccessor.get();
        if (ctx == null) {
            throw new HiveException("MapredContext is not set");
        }
        JobConf jobconf = ctx.getJobConf();
        if (jobconf == null) {
            throw new HiveException("JobConf is not set");
        }

        String dumped = HadoopUtils.toString(jobconf, regexKey);
        return val(dumped);
    }

}
